Sulfatases and depolymerases attacking chondroitin sulfates and chondroproteoglycans were detected in rat, dog and hog gastrointestinal mucosa. The enzymes responsible for these activities will be separated from one another and purified by fractional precipitation with ammonium sulfate and by adsorption chromatography on hydroxylapatite and by ion exchange cellulose chromatography. Localization of these enzymes in cell organelles will be determined by differential and density equilibrium centrifugation. Titers of these enzymes in stress-ulcer mucosa and in gastric juice will be determined to ascertain whether the release titer of these enzymes is related to diseased states. It appears that the gastric chondrosulfatase may differ from the chondrosulfatase of other tissues such as liver in that the former attacks the intact and high molecular weight chondroitin sulfate whereas the latter attacks the oligosaccharide or lower molecular weight substrate. The stomach and liver chondrosulfatases will be compared in terms of Km inhibition analysis and reactivity with antisera to further delineate their relationships. Gastric enzymes liberating dialyzable organic sulfate from sulfated glycoproteins also were detected, and these enzymes and site of cleavage will be studied. Comparative sulfation of polyanions by mucosa from stomach, intestine and colon also will be studied to elucidate the factors determining the qualitative and quantitative differences in sulfation exhibited by these tissues. Attempts will be made to alter the pattern and extent of sulfation by adding compounds from mucosa which exhibit relatively high sulfating ability to mucosa of low sulfating ability.